Despite immunization of high risk persons against influenza, annual epidemics continue to pose an important threat to the health of persons over the age of 65 years as well as to persons with cardiopulmonary and other high risk conditions. Healthy children are felt to be an important source for community transmission of influenza. Immunizing healthy school-aged children has been proposed as 1 strategy to protect high risk individuals; by immunizing children spread of influenza is prevented and persons at high risk for complications are protected. The goal of this planning grant is to develop a protocol of a cluster randomized trial which will test the effect of immunizing children in Hutterite colonies with inactivated influenza vaccine in order to prevent laboratory confirmed influenza and other outcomes in older adults and others at high risk for complications. The majority of Hutterites live in Alberta, Saskatchewan, and Manitoba where they practice communal farming on small colonies isolated from towns and cities. We propose a cluster randomized controlled trial among Hutterite colonies to test the hypothesis that high immunization rates ("70%) of healthy children with inactivated influenza vaccine reduces transmission of influenza to persons at high risk of complications. Randomization of these homogeneous, moderately sized colonies where there is regular spread facilitated by a communal lifestyle, but limited re-introduction because of relative isolation from outside community, represents a unique opportunity to test the hypothesis of indirect benefit under close to ideal conditions. Outcomes that will be assessed in the clinical trial include the following: laboratory-confirmed influenza, febrile respiratory illness, office visits for respiratory illness, otitis media, antibiotic prescriptions, school or work absenteeism hospitalizations, and death. The activities described in this proposed planning grant will lay the necessary ground work to conduct the randomized controlled trial. We believe that the trial we propose will lead to important data that can inform policy on influenza immunization strategy. [unreadable] [unreadable] [unreadable]